1. Field of the Invention
The invention pertains to an angle sensor with a fixed stator and a rotor rotating about an axis of rotation, where the stator has several optical-electronic sensor elements, each having the same design, being aligned in a plane vertical to the axis of rotation on a circular line in the perimeter direction concentric to the axis of rotation and being distributed across a range of perimeter angle, where said sensor elements cooperate with the coding provided on the rotor.
In particular, the invention pertains to an angle sensor for use in a steering device of a motor vehicle.
2. Background Art
Document EP 774 648 A1 describes an angle sensor of the kind referenced above, with a code ring with n, where n greater than 1, code ring segments having the same geometric design, each having the same coding, where the sensor elements and each code ring segment extend across a range of perimeter angle of 360xc2x0/n.
In the illustrated design example of this kind of sensor device, there are six optical-electronic sensor elements formed as bifurcated light barrier units each having the same spacing from each other and positioned on a perimeter angle range of 72xc2x0, where five code ring segments having the same coding, in conjunction with the six sensor elements, produce a one-step, linked, six-bit-code, so that the angular position within a segment can be unambiguously determined.
The device operates very precisely and dependably in a low-tolerance mechanical structure; however, certain deviations from the ideal configuration, such as a radial offset of rotor and stator with respect to each other, or a deviation of the track formed by the sensor elements from the factory-installed circular line, will allow the device to operate with correct measured results only along a limited perimeter.
Therefore, the problem of the present invention is to refine this kind of sensor device so that even greater mechanical tolerances can be accepted, such as those required due to the integration of the sensor device into a higher-order structural unit having several components, such as a steering column switch, for example, and/or a volute spring cassette as a kind of steering column tube switch module, and so that still a dependable function of the device will be assured.
This problem is solved according to this invention, in that the longitudinal axes of the optical-electronic sensor elements (i.e. in the case of the bifurcated light barrier units, for example, the connecting lines between an optical-electronic transmitter and the receiver allocated to it) are not arranged radial to the circular line on which these units are positioned in the perimeter direction, but rather are parallel to each other.